GTA brought to the School yard pretty much sums it up perfectly. Some small spoilers in here : P.
Also it's a pretty long game, I've beat all the story missions, and passed most of the classes and am only 78% done ;D.
Very sand-box style game, the first chapter is kind of boring because you can't leave the campus, but you get to soon enough, and the beginning is very important and interesting, so you probably won't care too much.
I picked up on the controls really quickly because there vrtually the same as GTA.
There is nice attention to detail in the world, seasons change, peoples attitudes toward you, differentiated character skins, not the same 3 skins repeated, the neighborhoods, all that stuff.
The character custimization is pretty cool, lots of clothes, haircuts and things, also there are tons of unlockable outfits.
Weapons are pretty fun, and innovative to say the least, my favorite was probably the spud cannon lol.
The classes (minigames) were pretty enjoyable, I never finished english 4 though :/, i'm still trying to in the "Endless Summer" chapter though.
I hated the one for art though, so tedious after you get past Art 3.
You get certain rewards for completing the different class levels, like completing shop 1 will get you a garage to store your vehicles.
Chemistry was pretty fun and had the best rewards by far.
They also have a hooker concept in the game, like in the GTA series after you had sex with a prostitute, your life would raise, if you make out with a girl (and have passed a certain class ;P ) it adds another health layer, which was pretty cool I think.
They also have a collection system, like in GTA the hidden packages, tags, photo opps, but these are rubber bands, I dunno why, still havent got them all.
Transportation, they had some cool stuff in there, Bikes, skateboard, go karts, mopeds etc, you can steal mopeds if you see someone with one, but the cops will bust you for not having a helmet on.
The world was very interesting lots of things to do, like the Carnival for instance, you can play the games, they had the test your strength type in there, dunk tank, shooting gallery, and some others, and by playing these you win tickets which can be redeemed for loads of things in the prize tent.
But you could also check out the freak show lol, I though the fat lady was just pretty nasty myself. You could participate in go kart races, ride the rides, one thing I wish that was open is the funhouse, you get to go in there for a mission one time, but that's it.
You can also partake in BMX races, which are pretty fun.
But there are tons of other things you can do around town, very interesting place Bullworth.
I really also enjoyed how the prefects would chase you, and the jocks sometimes, and the police sometimes :o , I do think it was a bit to easy to get away though.
There is a lot of things I probably left out, but you hopefully get the gist of the game, Bully is a great game, and if you liked any GTA the probability of you enjoying this is fairly high, so check it out if you haven't yet, a great experience awaits : ) .